Ageratina roanensis (Small) E.E. Lamont

Locations ofAgeratina roanensis (Small) E.E. Lamont in Virginia

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Botanical Name
Ageratina roanensis (Small) E.E. Lamont
Common Name
Appalachian White Snakeroot
Ageratina altissima (L.) King & H.E. Robins. var. roanensis (Small) Clewell & Wooten; Eupatorium rugosum Houtt. var. roanensis (Small) Fernald
Flora of Virginia Name/Status
Ageratina altissima (L.) King & H.E. Robins. var roanensis (Small) Clewell & Wooten
Ageratina roanensis represents plants of the Southern Appalachians that are generally larger than A. altissima in all dimensions and have longer involucral bracts with long, cuspidate apices. See Clewell & Wooten, 1971 (Brittonia 23:123-143) for the original circumscription as A. altissima var. roanensis. More recently, Lamont (2018, Phytoneuron 2018-77: 1-3) makes a fairly strong case for recognizing this taxon at species rank. He also cites Virginia specimens that extend the verified range a little northward to Floyd, Bland, and Giles counties, but all still at the higher elevations to which this taxon is restricted. Outside the Southern Blue Ridge, plants with intermediate characters that are not easily identifiable to variety have been noted (see Habitat notes). Pending further investigation, this taxon is mapped only in counties from which confirmed specimens have been collected.
High-elevation forests, especially cove forests and northern hardwood forests; also on balds. Locally common in the sw. mountains. Unequivocal Ageratina altissima var. roanensis is known from higher elevations of the Southern Blue Ridge, especially the Balsam Mountains (Grayson, Smyth, and Washington counties), where it is common, and very locally in Craig and Giles counties. However, it has been attributed by various sources to counties in the Ridge and Valley and the Northern Blue Ridge, ranging to nw. Virginia. Some, if not all, of these reports are referrable to large plants of var. altissima that approach var. roanensis in certain characters (see comments).
Native Status

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